DESCRIPTION: (Adapted from the Applicant's Abstract.) The research proposal consists of series of studies designed to define the effects of impulse/impact noise on cochlear structure and function. The first goal is to understand the relationship between the parameters of impulse and impact noise (peak, pressure, duration, number, repetition rate and spectrum) and their effects on cochlear sensitivity and pathology. The second goal is to understand the sequence of pathological changes in the cochlea associated with exposure to high levels of impact or impulse noise. The final goal is to begin to understand processes contributing to individual susceptibility to noise damage. In addition to investigating individual differences,the experiments will help to understand how the auditory system develops resistance to noise induced hearing loss. The results of this experimental program are important for developing noise standards. A consistent theme of the experiments is to develop a better understanding of how the Equal Energy Hypothesis describes the ear's reaction to impact/impulse noise.